07/25/2007 Env Bd Packet - Laserfiche WebLink

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• development on a site smaller than 2.5 acres, and single - family residential development on a site smaller than five acres (present Section 5). The proposed rule would delete this exemption and require all development meeting the applicable threshold to incorporate adequate erosion and sediment control precautions. • Permanent infiltration facilities require more care during construction to avoid soil compaction, soil surface smearing and sedimentation. District practice has been to include conditions in the permit for this purpose. The proposed rule would explicitly require the erosion control plan to address this need (Paragraph 3(e)). • The proposed rule clarifies the property owner's responsibility to inspect and maintain erosion and sediment control practices until a site is finally stabilized or the permit is assigned or transferred (Paragraph 6(c)). The specific requirement to inspect after each 0.5 -inch rainfall would be deleted. • A specific criterion for "final stabilization" - 70 percent density of vegetation and . ground cover - would be established (Paragraph 7(a)). • As proposed, the application would need to include a copy of any Stormwater Pollution Prevention Plan the property owner has prepared pursuant to an NPDES permit. VI. RULE E: FLOODPLAIN ALTERATION The primary change to the floodplain rule would be to substantially simplify it by departing from the present approach, which establishes two separate floodplain sectors within the watershed (present Section 3). Instead, the rule would impose a uniform standard requiring replacement, within the same floodplain, of any flood storage capacity lost by filling between the ordinary high water level and the 100 -year flood elevation (Paragraph 3(a)). The rule also would set explicit timing requirements on flood storage replacement: on- site replacement would need to be provided within the permit term, while off -site replacement would need to occur before any floodplain filling (Paragraph 3(a)). • The proposed rule also poses a provision that would allow fill or encroachment within the flood fringe where there is a formal delineation of floodway accepted by the 15